President Bush's nomination to be U.S. Ambassador to the United Nations, John Bolton, has pledged to cooperate with other countries to strengthen the world body.  The nominee is being opposed by Senate Democrats who say he is a polarizing figure.

John Bolton faced tough questioning [Monday] from the Senate Foreign Relations committee. Some members blasted him for his past criticism of the United Nations - an organization he has described as "irrelevant and corrupt."

Critics also say his support for unilateral action, such as the U.S.-led invasion of Iraq, could be a liability for a U.S. ambassador to the United Nations.

But, U.S. Secretary of State Condoleezza Rice has described Mr. Bolton, the Bush administration's former arms control chief, as a tough-minded diplomat who would be a strong voice for U.N. reform. And Mr. Bolton's supporters on the commitee say he is exactly the kind of diplomat needed to make the world body more effective.

Democratic senators, such as Joseph Biden, expressed doubts about that.

Joseph Biden

"We need a strong voice in New York that knows the UN and who can advance our reform agenda.  But we don't need a voice which people may not be inclined to listen to.  And I fear that knowing your reputation - and your reputation is well-known at the United Nations - people will be inclined to tune you out," says senator Biden.

Mr. Bolton says the U.N. has, in his words, "gone off track".  He said UN institutions need strengthening, and the world body needs to do more to prevent the proliferation of weapons of mass destruction, carry out a global war on terror and address humanitarian crises .

John Bolton

"Now, more than ever, the UN must play a critical role as it strives to fulfill its original promise.  And this effort demands decisive American leadership," says Mr. Bolton.

The Republican party head of the commitee, Senator Richard Lugar, acknowledged that Americans disagree about the relationship between the U.S. and the U.N.

"The nomination... has generated public debate on US policies toward the UN and on the degree to which the US should embrace multilateralism,” says senator Lugar.

But some Democratic Party members of the committee were not at the hearing for a debate. Former Democratic Party presidential nominee John Kerry attacked Mr. Bolton's record as an arms negotiator - especially in regards to North Korea.

"In North Korea, I think Mr. Bolton deserves a lot of credit for the abandonment of efforts that the Clinton administration made that effectively froze Pyongyang's plutonium program.  There's been a huge increase in the nuclear capacity of North Korea on your watch," says John Kerry.

The Senate Foreign Relations Committee will continue to question Mr. Bolton this week. If they vote in favor of his confirmation, the full Senate will consider the nomination.